Control apparatus for vehicles



Jan. 30, 1940. FISCHEL AL 2,188,834

CONTROL APPARATUS FOR VEHICLES.

Filed May 21, 1938 3 Sheets-Sheet 1 JNVENTORb W MM BY MW Jan. 30, .1940. E. FISCHEL- ET AL CONTROL APPARATUS FOR VEHICLES Filed May 21, 1938 3 Sheets-Sheet 2 INVENTO-RS Md $4M ATTORNEY.

Jan. 30,1940. E. FISCHEL ET AL 2,188,834 CONTROL APPARATUS FOR VEHICLES Filed May 21, 1938 3 Sheets-Sfiest 3 -Zlc a; K -4a' 35 a4 .35 Z 43 L as Z5 Z9 a3 l- Zlb 56 55 5k 45 54 f an 331: W

INVENTVORJ M 7304! BY M ATTORNEY.

Patented Jan. 30, 1940 Eduard Fischel, Berlin Charlottenburg, and Thiry, Berlin-Sudende, Germany, assignors to Siemens Apparate und Maschinen Gesellschaft mit beschrankter Haftung, Berlin, Germany, a'corporation of Germany Johannes mzlssurn APR 1 5.1941

Application-May 21, 1938, Serial No. 209,344

In Germany April 29, 1937 25 Claims.

This invention relates to control apparatus for trol surfaces are angularly displaced, in compensation for course or attitude deviations, by an amount which-is a function of the turning moment necessary to return the vehicle to the original course or attitude.

A further object is to provide novel automatic pilot means for aircraft wherein equal deviations from a predetermined attitude are corrected during substantially equal periods of time for all speeds.

Another object is to provide novel means. of

the above character, wherein the compensating L control surface displacement for course deviations takes place at a speed which is a function of the speed of the craft, and also of the amount of said displacement.

A further object is to provide novel control means for aircraft, marine vessels, and the like, which will quickly correct for deviations of the vehicle from a predetermined course.

An additional object is to provide novel automatic pilot means, for vehicles such as aircraft. which means are responsive to the forces acting on the control surface which forces are, in turn, dependent upon the air speed of the craft.

Another object is to provide novel automatic servo-motor is controlled by additional means,

approximately equal for all air speeds. This is pilot means for aircraft wherein the compensating control surface displacement is a function of the air speed and the altitude.

' A further object is to provide novel vehicle control means wherein an air speed gauge aids in controlling the amount and speed of the angu- 40 lar displacement of control surfaces in compensating for a deviation from a predetermined attitude. 1 I

The above and further objects and novel'features of the invention willmore fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended to define" turn, is a direct function of the air speed and an 'means are constituted by a magnetic compass Fig. 1 is a schematic diagram f one embodiment of the invention; v

Fig. 2 is a schematic diagram of a second embodiment of the invention; and

Fig. 3 is a schematic diagram of a third embodiment ofthe invention.

The form of the invention illustrated, by way of example, is an automatic course control de- .vice for aircraft and is constituted by a direction indicator which is adapted for transmitting deviations from a predetermined course to a servomotor which governs a rudder or control surface. In cooperation with said direction indicator, the

which are responsive to the air speed, in such a manner that the rudder isdisplaced by an amount which will produce the proper turning moment necessary 'to restore the craft to the predetermined course. In order that course deviations may be corrected smoothly and uniformly, speed control means are provided for said servo-motor whereby the control surface is angularly displaced at such a velocity that the time interval required to correct a given course error will be accomplished by controlling said speed in response to either the Mamie air pressure or to the angular displacement of the control surface.

One embodiment of the present invention is 11 lustrated in Fig. 1 wherein novel means are pro-. vided for controlling the amount and the angular' velocity of deflection of the rudder of an aircraft. The amountof deflection is governed in response to the dynamic air pressure which, in

inverse functionpf the altitude. The angular velocity of deflection is also governed by said dynamic air pressure'whereby saidvelocity is high for low pressures and low for high pressures. It is desirable that the deflection be an inverse function of the altitude because at a high altitude the air density is low; consequently, a greater deflection is necessary to produce a given turning moment than when'ata low altitude. The novel having a needle I]! mounted in a conventional manner above a disc Illa. The compass is adapted for serving as a direction transmitter, the

disc I in: being provided with contacts H and II which engage a contact. l3 in accordance with a right and left course deviation, respectively. The I contact l3 is attached to one extremity of needle Ill. The direction transmitter'may' be adjusted to a desired course, for example, by means of a flexible s'haft' ll to which are attached worms II I5, l6 meshing, respectively, with a worm wheel '!1 connected to disc 16a and with a worm wheel l8 of a compass disc l5 having an index mark l9a. The shaft I4 may be rotated by a'suitable hand knob 20.

Operatively connected to the above-described direction transmitter is an amplifying arrangement constituted by a rotary magnet 2| which is 28 attached to said armature, is normally held in a centralized position by opposed springs 29,

29, and the compass deviations, as reflected by armature movements; are transmitted by said arm to a conventional control valve 30 of a hydraulicservo-motor 3 I, for example, by means of a rod 32 which is pivotally connected to arm 28. Valve 30 moves within a cylinder 33 having pressure agent inlet 34, exhaust ports 35, 35, and conduits 33a, 33b to motor 3|. A piston 36 having a piston rod 37, of said servo-motor, is operatively connected to a control surface 38, for example, a Vertical rudder of an aircraft.

Means are provided for returning valve 36 to the closed position in response to an electric current which is governed by the dynamic-air pressure and also by the amount of. the angular displacement of the rudder, the dynamic air pressure being a function of the air speed. The current governing means comprise a pressure gauge 39 having a diaphragm 40 and a suitable tube portion 4|, the open end of which is exposed to the air stream external to the aircraft such that the air pressure acts' upon one side of said diaphragm. A spring .(not shown), which is adjustable in tension, acts upon the opposite side of the diaphragm.

I11 order that diaphragm 40inay control the potential of an electric current which governs the servo-motor, in a manner tobe later set forth,-a potentiometer resistance 42 is provided having a resistance coil 43 over which slides a contact arm 44.

. potentiometer are provided for returning the control valve 30 to. the closedposition in ac 'sition to that of coil 22.

of piston, 36, comprising a bridge connection 41 Arm 44 is pivotally mountedat 44a and is operatively connected to diaphragm posed thereto, are connected by leads 55, to coil 48 upon armature 210. The remaining- .two diagonally opposed points of bridge 41 are in connectionby leads 51, 58 with one extremity of resistance 43 and with contact arm 44, re- I spectively, whereby the potential to said bridge is governed. In order that bridge 41 may produce. a smoothly changing current for armature coil 48, suitable means (not shown) may be provided for movably mounting contact 54 10 and operatively connecting the same to servomotor 3| or to compass H). j

It is highly desirable that the apparatus compensate for course deviations as smoothly and as quickly as possiblev and also that the time 15 interval for compensating for a given course error be approximately equal for all air speeds. When the aircraft is traveling at low speed and a course deviation occurs, a greater compensating rudder deflection is required than when .as above described, governs the servo-motor control valve 30. A contact arm 60 pivotally mounted at Ma and connectedto the diaphragm 40 by rod 45 controls said variable resistance. The coils 6|, 6| upon pole pieces 2"), Nb, for example, are in series upon a lead 62 with resistance 59. Lead 62 is connected across the terminals of the energy source 46, the current of which is regulated by the above arrangement such that the strength of 'the field of said coils is low for high dynamic pressures and high for low I pressures.

. In operation, a deviation from a predetermined course will permit a current to flow to armature coil 22. Armature He will be displaced against the pressure, of springs 29, 29 and will open control valve 30, thus permitting the pressure agent to act upon servo-motor piston 36 "to move rudder 38. As the servo-motor piston rod 31 is longitudinally displaced, the contact arm 53 of bridge 41 will move ,therewith ,over resistance arm 49 or 56 and will pe'rmita current to flow through said bridge in accordance with the displacement-of the contact arm from the central position. This current flows to armature coilwhich- 'controls' the current-to a coil 48 upon Y armature 2|c, the field of which acts in oppo- Y The arms of bridge 41 are constituted, for example, by ohmic resist-.

ances 49, '50and 5|, 52. A contact arm 53, op-

eratively connected to piston rod 31 of servomotor'3l, is slidable over the bridge arms 49, 56.

Piston 36 and rudder 38 are arranged in a centraliz'ed position when contact arm 53 is centered between resistance arms 49,- 50. arm 53 and a second contact 54, diagonally op- The contact 46, the field of which opposes that of coil 22. and thus tends to counteractr the motor action thereof. The dynamic air pressure acting upon 55: V

diaphragm 40 controls the potential of the current to bridge 41 by meanspf the variable resistance 42. Consequently, the displacement of rudder 38 will be a function of the dynamic air pressure and hence a function of the proper turning moment necessary to restore the craft to the original course. The dynamic 'air'pressure acting on diaphragm 40, by controlling resistance 59, controls the field strength of coils 6|, 6! of the rotary magnet. The field strength 65 of these coils is inversely proportional to said dynamic pressure.

Consequently, the servo: motor will operate and the control surface,,.38- will move with greater 'velocitywhen the/craft is at a low air speed than when at a high speed,

thus causing the time required to correct a given course error to be approximately 'equal for all airsneds-i I For a given air s e the d i pres-j.

sure will decrease withlan increase in altitude? rudder I5 by means of a. cross-lever 88 centrally due to the decrease in air density. ponsequently, for the same air speed, a greater rudder defiection will be produced at a high altitude than at a low altitude.

In the form illustrated in Fig. 2, a second embodiment of the apparatus'is shown wherein novel means are provided for controlling the deflection of a control surface and the angular velocity at which the deflection takes place, comprising a direction indicator and an associated rotary magnet,,both of which are identical'to those shown in'Fig. 1 with the exception that in the present embodiment the field of the rotary magnet is constant in strength and only the single coil 22, connected to the direction indicator, is wound upon the armature.

- The rotary magnet is operatively connected to a control valve 63 for a hydraulic servo-motor 64, by means of a rod 65 which connects arm 23 of said magnet to one extremity of a differential lever 66. The opposite extremity of lever 66 is positioned in a manner to appear later.' Intermediate these extremities, a valve rod 63a for valve 63 is connected. Valve 63 moves Within cylinder 61 having exhaust ports 68, 68 at either extremity thereof and a central inlet port 69. The cylinder is in communication with the motor 64 by means of conduits I9, II which enter said motor at opposite extremities thereof. A servo-motor piston I2, having arod I3, is operatively connected to a crank arm I4 which, in'the form shown, is rigidly,

attached to a control surface or rudder I5 pivotally mounted at 15a.

Means are provided in, combination withthe above described apparatus whereby the control surface displacement, in comlpensation for a course error, is determined not only by said error,

, as transmitted by thecompass I9, but also by surround a piston rod I9 upon which the piston is mounted. Conduits 89, 8I, connected to the gauge, are also connected to conduits I9, 'II, re-

spectively, and communicate the pressure differential in the latter two conduits to said gauge.

A conventional hydraulic or pneumatic dashpot 82 is attached to piston rod I9 of gauge I6, and cushions the piston movements which position the extremity of lever 66, said extremity being opposite to that controlled by rotary magnet 2|.

In connection with the first embodiment, the angular velocity of the rudder deflection is a function of the dynamic air pressure as measured by a gauge, 1. e., the angular velocity is indirectly dependent upon the amount .of the rudder deflection; however, in the present embodiment, the rudder velocity is directly dependent upon the amount of rudder-deflection. Novel means are provided for' so governing'this velocity comprising a unidirectional coupling constituted by a bifurcated member 83 having "fingers 83a, 8311 each of which are provided with slotted arcuate end portio 8'4, 84-. Member 83 is adapted for longitudina displacement, being mounted in a bearing 85 and operatively connected to mounted at 15a. and rigidly attached to said rudder. Pins 81, 81 at either extremity of lever 86 extend into the slots of the end portions 84-,

84. The arcuate slots are'so formed that when I arm I4 is moved equal amounts in either a clockise. or counter-clockwise direction from the central position, as shown in Fig. 2, the member 83 is displaced longitudinally the same amount in the direction of the arrow 85a.

The movements of member 83 are amplified, for example, by a rotary magnet arrangement which is controlled by a variable resistance. The free extremity of member 83 is linked to an arm 88 which is pivotally mounted at 88c. Arm 88, having an electric contact 88b at its free extremity, slidably engages a variable resistance 89 which is connected by a lead 99a to an armature coil 99 upon an armature 9I o'f-a rotary magnet 92 having a stator 93. Coil 99 is also connected to the arm 88 at 88aand hence to contact 88b through a suitable source of electric energy 94. In order that contact 8822' may be normally held at a zero position upon resistance 89, a motor having a shaft 95a is'connected, through a worm and wheel 96, 91, to a conventional friction coupling 98, 98 upon a shaft 99. Shaft 99 is connected to arm 88 by bevel gears I99, I99a, respectively, whereby the arrangement urges said arm in a clockwise direction towards the zero position shown in Fig. 2.

Armature 9| is operatively connected to a pressure regulating valve which governs the pressure of the medium energizing the servo-motor 64. The-connection comprises an arm I9I attached to said armature and yieldin'gly urged in a clockwise direction by a spring I92.. Arm IN is pivotally connected to a bifurcated portion. I98

which positions a valve rod I94 of a pressure regulating valve I 95 having a housing I96 which. in turn, is provided with a valve seat I9'I. Valve seat I9I constitutes the 'mouth of an inlet conduit I98 which is connected to said valve housing. An exhaust port for said housing is provided at I99.

The pressure regulating arrangement is operatively connected to servo-motor 64 by means of conduit I I9 which connects conduit I98 to the control valve cylinder at'inlet 69 therein The exhaust ports 68, 69 in said cylinder and port i I99 in housing I96 are in communication with a.

common exhaust conduit III.

Between the fingers of the bifurcated member I93 is" a mietal portion having a suitable bore through which the valve 'rod extends. Surrounding the valve rod and interposed between the valve I95 and said metal portion is a coil spring I I2 which resiliently urges said valve towards seat I91. Adjusting means (not shown) are provided for governing the normal tension of spring II2 whereby the pressure of the working agent andthe sensitiveness of the pressure regulator is controlled.

In operation, a deviation from a predetermined which time the piston II will have moved against the pressure of springs I8, I8 to close the valve 63 by means of the differential lever 66. The

movements of piston TI are smoothly cushioned by dashpot 82.

When rudder 15 is in the centralized position, the bifurcated member 83 is in the zero position (Fig. 2) and exerts no turning moment upon arm 88. Motor 95, by'means of friction coupling 98, 98, is efiective to yieldingly urge arm 88 in a clockwise direction whereby the arm is held in the new position upon resistance 89. In this position, the coil 90 of rotary magnet 92 is not energized and spring I02 acting through armature erm I8! is effective to hold bifurcated memher i is at-an adjusted tension which will permit a defiiie'd leakage of the pressure agent past valve A95. The agent flowing to the servo-mptor'in conduit H9 from conduit I98 is consequently reduced in pressure, and the speed with which the servo-motor operates will be proportional to this reduced pressure. A deflection of rudder vl5 from the central position will longitudinally move member 83 in accordance therewith. Arm 88, against the action of coupling 98, 98, will be displaced from the zero position upon resistance 89,

coil 90 will be energized, and armature 90 will move ina counter-clockwise direction against the pressure of spring I02. The member I03 will thus be urged downwardly, spring H2 will be compressed, and the quantity of the pressure agent leaking past .valve I05 will-be reduced. As the leakage past the valve is reduced, the pressure acting upon motor piston 12 and the speed of the motor will increase. Consequently, the angular velocity of the rudder l5 willnprogressively increase as therudder deflection increases up to the ,point where the servo-motor valve 63 undergoes the closing action produced by pressure gauge 16, as above mentioned. During the closing of valve 83, rudder l5 smoothly anduniformly decelerates in angular velocity until it comes to rest.

In the form shown in Fig. 3, a third embodiment of the invention is illustrated constituting a combination of the elements of the embodiment of Fig. 1 with the exception that no means 7 are provided for controlling the strength of the field coils upon pole pieces 2lb, 2 lb.

The operation of this embodiment is similar to that of the first embodiment with the excep- 2! moves is a function only of the strength of the field of armature coil 48 coacting with the constant fields of coil 22 and of the coils (not shown) upon pole pieces 2 I b, Mb;

There is thus provided a novel course control device wherein the corrections for course deviations are functions of the proper tin'ning moment to restore the craft to the original course. The apparatus is elfective to govern the speed at which deflections of the control surface occur suclr that large deflectionstake place rapidly relative to small deflections, whereby equal course deviations are corrected in approximately equal periods of time for all air speeds.

Although only three embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto; For example, electric or penumatic servo-motors may be employed instead of the hydraulic type here used. The apparatus insteadof controlling a rudder of an aircraft whereby the course is governed may be adaptedfor controlling other control surfaces,

for example, surfaces governing the altitude of 83 in its uppermost position. Spring 2 tion that the angular velocity at which armature a dynamic air pressure gauge is employed; how-. ever, this may be replaced by suitable means for measuring dynamic water pressure if the apparatus is to be associated with marine vessels. The pressure regulating device 'for controlling the servo-motor speed in the embodiment of Fig. 2

may be operatively connected to the variable resistance 59 ofFig. 1. Also, the dynamic air pressure gauge of Fig. 1 may be employed to control the pressure regulating valve of Fig. 2. It is also possible to substitute the pressure gauge E6 of Fig. 2 for the dynamic air pressure gauge of Fig. 1, wherein the former controls the potential to bridge 41 of Fig. 1. Various changes may also be made in the design and arrangement of parts illustrated without departing from the spirit and scope of the invention, as will now be understood. by those skilled in the art. For a definition of the limits of the invention, reference will be had primarily to. the-appended claims.

What is claimed is: v

1. The combination with an attitude indicator for a vehicle, of a servo-motor, a control valve therefor, a control surface operatively connected to said-servo-motor, means for governing said control valve in response to deviations from a predetermined indication of said attitude indic'ator, means acting in opposition to the firstnamed means in response to the vehicle speed, andmeans for controlling'the velocity of said servo-motor in response to said vehicle speed.

2. The combination with an attitude indicator for aircraft, of a servo-motor, a control surface operatively connected thereto, means for actuat' ing said servo-motor in response to deviations from a predetermined indication of said attitude indicator, means for arresting the movement of said servo-motor in response to the air speed, and means for governing the velocity of said servomotor also in response to the air speed. 4

3. The combination with an attitude indicator for aircraft, of a servo-motor,, a control valve therefor, a control surface operatively connected to said servo-motor, means for opening said mined attitude, means for closing said valve in response to the deflection of said control surface' s and to the air speed, and means for controlling the speed of opening and closing said valve in response to said air speed.

4. The combination with an attitude indicator .for aircraft, of a servo motor, a control valve ,therefor, means for opening'said valve in response to a deviation from a predetermined atresponse to the displacement of said control surface. Y,

5. In apparatus of the class described, an attitude indicator, a servo-motor, a control valve therefor, a control surface for a vehicle operatively connected to said-motor, means for governing said valve in response to changes from apredetermined indication of said attitude indicator, means for controlling the speed of operation of said motor in response to the dynamic pressure of the fluid sustaining said vehicle, and means for'continuously opposing the action of the first-- named governing meansin accordance with said dynamic pressure and also in accordance with the deflection of said control surface;

6. The combination in a vehicle of a control valve in response to deviations from a predeter-- the Furthermore, in the first embodiment, surface therefor, power means for actuating said "u control surfaces, and means controlling the speed of operation of said power means including means responsive to the velocity of said vehicle relative to the medium sustaining the same. i

7. The combination i a vehicle of a control surface therefor, power giejns for actuating said control surface, and means controlling the speed of operation of said power means including means responsive to the deflection of said control surface from a predetermined position.

8. In an automatic pilot apparatus, a direction indicator, a. servo-motor, a control surface operativgly connected to said motor, means for actuatin said motor when a deviation occurs from a predetermined direction indication, and means qforcontrolling the speed of said motor whereby said speed is a direct function of the displacemerit of said controlsurface. v

9. The combination in a vehicle of a control surface therefor, power means for actuating said control surface, attitude responsive means for actuating said power means in response to a deviation from a predetermined attitude, and

rmeans. for governing said power means whereby the amount and the speed of the displacement of said control surface is responsive to the velocity of said vehicle.

10. In apparatus of the class described, a control surface for a vehicle, power means for actuating said control surface, speed control means for said'power means including means responsive to the velocity of said vehicle relative to the medium sustaining the same, and a uni-directional coupling member operatively connecting said speed control means and' said control/ surface.

- 11. In apparatus of the class described, a con-, trol surface for a vehicle, power means for actuating said control surface, speed control means for said power means including means responsive to the deflection of said control surface, a control member for said speed control means, and means for yieldingly urging saidcontrol member to -a predetermined position.

12. In apparatus of the class described, a con-'- trol surface for an aircraft, power means for actuating said control surface, deflection control means for said control surface including means for governing said power means in accordance with the air speed, means for governing the speed of said power means in accordance with the defiection of said control surface, and means for operatively connecting said power means and speed control means including a coupling whereby angular movements of said control surface in both clockwise and counter-clockwise directions, from a predetermined position, are-translated into linear movements in one direction. V

13. The combination with a vehicle, of attitude responsive means, a control surface for said vehicle, power means for governing said control surface, means for actuating said power means in accordance with said attitude Y responsive means, means for arresting said power means in response to the dynamic air pressure and to the deflection of said control surface, and means acting simultaneously with said last-named means for controlling the speed of said power means.

14. The combination with attitude responsive means for a vehicle of power means, a control member for said power means, means for moving said control member-in accordance with said attitude responsive means, means for moving said member in a direction opposite to the first.

movement in response to the pressure of an agent energizing said power means, and pressure regulating means for said agent, the latter means being governed by the action of said power means.

15. In apparatus of the class described, a control surface for a vehicle, power means for actuating said control surface, speed control means for said power means including means responsive to the deflection of said control surface, means for controlling the amount of movement of said power means'including means'responsive to the counteracting pressure ,upon said control surface, a control member for said speed control means, and means including a friction coupling for yieldingly urging said control member to a predetermined position.

16. The combinationwith a vehicle of a servo- Inotor, a vehicle control surface operatively connected thereto, attitude responsive means operatively'connected to said servo-motor, and dynamic fluid pressure responsive means for continuously opposing the action of said attitude responsive means upon said power means.

17. In apparatus of the class described, a control surface, power means for actuating said control surface, means responsive to a dynamic fluid said power means, and. means for continuously.

counteracting the effect of said attitude respon sive means in accordance with said dynamic fluid pressure and in accordance with the deflection of said control surface. q

18. In apparatus of the class described, a control surface for a vehicle, power means for -actuating said control surface, a-control member for said power means, attitude responsive means for moving said control member from a'predetermined position, and dynamic fluid pressure responsive means for returning said member to the predetermined position.

19. The combination with a control surface for a vehicle of power means for actuating said control surface, control means for said power means, an electric bridge operatively connected to said power means whereby the resistances in said bridge are varied, said bridge also being operatively connected to said control means, and dye namic pressure responsive means for controlling the potential across said bridge. a

20. The combination with power means, of con-:

trol means therefor, means for displacing said control means from a predetermined position, and

therefor, meansfor opening said valve in response to a deviation from a predetermined attitude, a control surface operatively connected to said servo-motor, means for closing said valve in response to the pressure of an agent actuating said motor, 'meansfor controlling said pressure in'response to the displacement of said control surface, and means for adjusting the sensitiveness of said last-named means.

22. The combination with a control surface for a vehicle of power means for actuating said control surface, control means for said power means, and an electric bridgeoperatively connected to said power means whereby the resistances in said bridge are varied, Find means operatively connecting said bridge to said control means. 7 23. The combination with a control surface for a vehicle of power means for actuating said control surface, control means for saidpower means, and means controlled by the differential variation in the power supplied by said power means for controlling said power means.

24. The combination in a vehicle of a control surface'therefor, power means for actuating said control surface, and means controlling the speed of operation of said power means comprising means responsive to the velocity of said vehicle relative to the medium sustaining the same, and means responsive to the deflection of said control surface from a predetermined position.

25. In an automatic pilot for aircraft and the like, the combination of a servo-motor, means responsive to deviation of the craft about an axis thereof for controlling said servo-motorin ac cordance with said deviation, 9. control surface connected to said servo-motor for actuation by deflection of said control surface from, a pre- 10 determined position.

EDUARD FISCHEL. JOHANNES THIRY. 

